Bitcoin is flirting with a test of this year’s lows following a cryptocurrency selloff that again pushed the sector’s overall market value below $1 trillion.

The largest digital token has shed more than 6% so far this week and was trading at $18,620 as of 10:28 a.m. in Singapore. Crypto market capitalization has fallen by a similar proportion in the past 24 hours, according to CoinGecko.

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Surging real interest rates are heaping pressure on a range of risk assets and crypto is no exception. The retreat in Bitcoin is taking it closer to a nadir of about $17,600 that was hit in June in the wake of blowups at crypto lenders and hedge funds.

“The macro narrative is very hard to be able to let go and will drive risk assets,” Kevin Loo, head of investment insights at IDEG Asset Management Ltd., said. “Bitcoin is below $20,000. We have been here before and it’s likely that we could actually go slightly lower.”

At the same time, there remains residual optimism from the upcoming upgrade of the Ethereum network, which some analysts hope will draw investment flows into Ether and other digital assets.

“Bitcoin was at $3,000 in the first crypto winter and if you measure trough to trough, the trend is we are heading higher in the longer term,” Loo said.

The MVIS CryptoCompare Digital Assets 100 index of the largest tokens is down about 60% this year. Bitcoin has tumbled from a pandemic-era peak of almost $69,000 in November last year.